package org.apache.cassandra.cache;
/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
import java.io.DataOutputStream;
import java.io.IOError;
import java.io.IOException;
import java.util.Set;
import com.googlecode.concurrentlinkedhashmap.ConcurrentLinkedHashMap;
import com.googlecode.concurrentlinkedhashmap.EvictionListener;
import com.googlecode.concurrentlinkedhashmap.Weighers;
import org.apache.cassandra.io.ICompactSerializer3;
import org.apache.cassandra.io.util.MemoryInputStream;
import org.apache.cassandra.io.util.MemoryOutputStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Serializes cache values off-heap.
*/
public class SerializingCache<K, V> implements ICache<K, V>
{
private static final Logger logger = LoggerFactory.getLogger(SerializingCache.class);
private static final int DEFAULT_CONCURENCY_LEVEL = 64;
private final ConcurrentLinkedHashMap<K, FreeableMemory> map;
private final ICompactSerializer3<V> serializer;
public SerializingCache(int capacity, ICompactSerializer3<V> serializer, String tableName, String cfName)
{
this.serializer = serializer;
EvictionListener<K,FreeableMemory> listener = new EvictionListener<K, FreeableMemory>()
{
public void onEviction(K k, FreeableMemory mem)
{
mem.unreference();
}
};
this.map = new ConcurrentLinkedHashMap.Builder<K, FreeableMemory>()
.weigher(Weighers.<FreeableMemory>singleton())
.initialCapacity(capacity)
.maximumWeightedCapacity(capacity)
.concurrencyLevel(DEFAULT_CONCURENCY_LEVEL)
.listener(listener)
.build();
}
private V deserialize(FreeableMemory mem)
{
try
{
return serializer.deserialize(new MemoryInputStream(mem));
}
catch (IOException e)
{
logger.debug("Cannot fetch in memory data, we will failback to read from disk ", e);
return null;
}
}
private FreeableMemory serialize(V value)
{
long serializedSize = serializer.serializedSize(value);
if (serializedSize > Integer.MAX_VALUE)
throw new IllegalArgumentException("Unable to allocate " + serializedSize + " bytes");
FreeableMemory freeableMemory;
try
{
freeableMemory = new FreeableMemory(serializedSize);
}
catch (OutOfMemoryError e)
{
return null;
}
try
{
serializer.serialize(value, new DataOutputStream(new MemoryOutputStream(freeableMemory)));
}
catch (IOException e)
{
throw new IOError(e);
}
return freeableMemory;
}
public int capacity()
{
return map.capacity();
}
public void setCapacity(int capacity)
{
map.setCapacity(capacity);
}
public boolean isEmpty()
{
return map.isEmpty();
}
public int size()
{
return map.size();
}
public void clear()
{
map.clear();
}
public V get(Object key)
{
FreeableMemory mem = map.get(key);
if (mem == null)
return null;
if (!mem.reference())
return null;
try
{
return deserialize(mem);
}
finally
{
mem.unreference();
}
}
public void put(K key, V value)
{
FreeableMemory mem = serialize(value);
if (mem == null)
return; // out of memory. never mind.
FreeableMemory old = map.put(key, mem);
if (old != null)
old.unreference();
}
public void remove(K key)
{
FreeableMemory mem = map.remove(key);
if (mem != null)
mem.unreference();
}
public Set<K> keySet()
{
return map.keySet();
}
public boolean isPutCopying()
{
return true;
}
}